Chewable and lozenge dosage forms are preferred by individuals who have difficulty swallowing tablets and capsules. Frequently, sweetners and flavors, along with diluting agents have been utilized as fillers in an attempt to minimize unpleasant or bitter taste of pharmaceutical active ingredient.
Many drugs, in particular drugs containing amine or amido groups or salts thereof, often have a strong bitter taste. Without proper taste-masking, such drugs cannot be adapted into acceptable tasting chewables and lozenges. One example of a bitter amino drug is dimenhydrinate. In addition to its bitter taste, dimenhydrinate produces a numbing effect that is equally as unpleasant.
Taste-masking techniques using various sweeteners, amino acids, acids, flavors and adsorbents have been unsuccessful in masking the taste of dimenhydrinate or if the taste is somewhat masked, the resulting product is therapeutically ineffective. One method involves the enteric coating of bitter tasting drugs with various copolymers. However, enteric coating has been ineffective. The coating of fine particle materials is usually unsuccessful and the coatings of granular particles are readily ruptured by chewing and compression. In addition, most coatings do not have an acceptable in vivo drug releasing mechanism.
Cation-exchange resins have been used to adsorb amine drugs for sustained release action and taste-masking. The widely used cation-exchange resins are polysulfonic acid and polycarboxylic acid polymers. In addition rice endosperm has been used to mask the taste of drugs utilizing its properties of stickiness and insolubility to physically entrap the drug molecules. However, neither technique has been effective in masking the bitter taste or numbing effect associated with dimenhydrinate.